The present invention relates to a test socket of a semiconductor device to be used, for example, to connect a semiconductor package having a ball-shaped external terminal projected from the package bottom to test equipment.
A conventional test socket of a semiconductor device will be explained by referring to FIGS. 1 to 3.
Firstly, the first prior art will be explained referring to FIG. 1. FIG. 1 is a cross sectional view showing a basic constitution of a contact member 1 of a spring probe pin type test socket. The spring probe pin type test socket is a test socket for executing a characteristic evaluation test of, for example, an FBGA (flat package ball grid array) IC (integrated circuit) 2 in which many contact members 1 are installed in the test socket. Each of these contact members 1 is structured so as to receive a ball-shaped external terminal 3 made of solder projecting from a bottom of a package of IC 2 with a concavity at an upper end thereof being supported by a pin support member not shown in the drawing. The lower end thereof is in contact with a contact pad 5 of a test board 4 corresponding to the external terminal 3 of the IC 2. External terminal 3 and pad 5 are thus connected to be conductible to each other, thereby DC characteristic evaluation or AC characteristic evaluation such as the high frequency characteristics and high-speed characteristics are carried out.
The contact member 1 has a metallic cylindrical case 6 with an upper end closed, a compression spring 7 housed in the case 6 for generating compression force in the axial direction, and a contact end 8 projecting downward from a lower end opening of the case 6. An upper end of the contact end 8 is connected to a metallic plunger 9, which is compressed by the spring 7 in the cylindrical case 6. Furthermore, at the upper end of the case 6, a concavity 10 is formed. The characteristic evaluation test of the IC 2 is executed under the condition that the external terminal 3 on the bottom of the IC 2 is pressed against the upper end concavity 10 of the contact member 1 installed to the test socket and that the contact end 8 of the plunger 9 projected downward is pressed against the contact pad 5 of the test board 4 of the test equipment at the same time.
However, the contact member 1 of the spring probe pin type test socket has a line length of, for example, 3 to 5 mm and has an inductance of 1 nH to 1.5 nH or so due to the structure in which the upper end concavity 10 and the contact end 8 are respectively pressed against the corresponding external terminal 3 and contact pad 5 so as to conduct to each other by the plunger 9 compressed by the spring 7 housed in the case 6 and connected. As a result, at the time of evaluation of the characteristics at a frequency of several GHz, the line length must be shorter. However, due to the structure of the spring probe pin type test socket, it is difficult to shorten the line length. Thus, a test socket for high frequency having a short line length and low inductance must be used which means a replacement of the test socket.
Next, the second prior art will be explained referring to FIG. 2. FIG. 2 is a cross sectional view showing a basic structure of a contact member 11 of a sheet type test socket. In FIG. 2, the contact member 11 is a test socket for executing the characteristic evaluation test of the IC 2 of the FBGA type described above, which is structured so that many metallic wires 13 are embedded overall a sheet-like insulating base 12 at a fine pitch and are inclined to a surface of the sheet.
At the time of conducting the DC characteristic evaluation or the AC characteristic evaluation such as the high frequency characteristics and high-speed characteristics, the contact member 11 of the test socket is arranged between the IC 2 and the test board 4 of the test equipment. The external terminal 3 of the IC 2 and the corresponding contact pad 5 of the test board 4 are arranged facing to each other across the contact member 11. Thereafter, the external terminal 3 and the contact pad 5 are pressed against the contact member 11. With the arrangement, a part of the wires 13 obliquely embedded in the insulating base 12 and in contact with the external terminal 3 are also in contact with the contact pad 5 and thereby being made conductive to each other.
In the contact member 11 of the test socket having the structure described, the length of the oblique metallic wires 13, that is, the line length is about 1.1 mm when the thickness of the insulating base 12 is about 1 mm, for example, which is shorter than that of the first prior art and the inductance is 0.2 nH or less, which is also lower than that of the first prior art. As a result, characteristics at a frequency of several GHz can be evaluated.
However, in the test socket of the second prior art, solder dust or package dust adhered on the surface of the external terminal 3 is also adhered on the surface of the contact member 11 in contact with the external terminal 3 of the IC 2 when the IC 2 characteristic evaluation test is executed many times. When the characteristic evaluation test is continued further, the adhered dust remained and piled increases contamination, which impedes a result of the characteristic evaluation test. Therefore, whenever the contact count reaches about 1500 times, for example, the contact member 11 must be frequently cleaned for which a great deal of time is required.
In the test socket, on the other hand, the cost is very high due to the structure of the contact member 11 in which the metallic wires 13 are arranged regularly overall the insulating base 12.
Next, the third prior art will be explained referring to FIG. 3. FIG. 3 is a cross sectional view showing the basic structure of a contact member 14 of a sheet type test socket for executing the characteristic evaluation test of the IC 2 of FBGA described above. The contact member 14 holds many conductive elastic contactors 16 at a position corresponding to the external terminal 3 on the bottom of the package of IC 2 of the sheet-like insulating base 15. Each of the elastic contactors 16 is formed passing through the insulating base 15 and having an upper contact part 16a and a lower contact part 16b respectively projected from an upper and a lower surface of the insulating base 15.
At the time of conducting the DC characteristic evaluation and the AC characteristic evaluation such as the high frequency characteristics and high speed characteristics, the contact member 14 of the test socket is arranged between the IC 2, so that the test board 4 of the test equipment and the contact surface of the lower contact part 16b of the elastic contactor 16 is positioned right above the contact pad 5 of the test board 4. Further, the corresponding the external terminal 3 of the IC 2 is positioned right above the contact surface of the upper contact part 16a of the elastic contactor 16. Thereafter, the external terminal 3 is pressed against the contact surface of the upper contact part 16a of the elastic contactor 16 installed on the contact member 14 and the contact surface of the lower contact part 16b of the elastic contactors 16 is pressed against the top of the contact pad 5 of the test board 4. With the arrangement, the external terminal 3 and the contact pad 5 are made conductive to each other via the elastic contactor 16.
When the total height of the elastic contactor 16 held by the insulating base 15, that is, the line length is selected as about 0.7 mm, for example, in the contact member 14 of the test socket having the structure described, it is shorter than that of the second prior art having such a low inductance as 1.0 nH. As a result, characteristics at a higher frequency than that of the second prior art can be evaluated.
However, in the test socket described, as well as in the second prior art, solder dust or package dust adhered on the surface of the external terminal 3 is also adhered on the surface of the elastic contactor 16 of the contact member 14 in contact with the external terminal 3 of the IC when the IC 2 characteristic evaluation test is executed many times. When the characteristic evaluation test is continued further, the adhered dust remained and piled increases contamination, which impedes a result of the characteristic evaluation test. Therefore, whenever the contact count reaches about 1500 times, for example, the contact member 14 must be frequently cleaned for which a great deal of time is required.
The present invention was made under the circumstance described above and has an object to provide a test socket for a semiconductor device which enables the high frequency characteristics evaluation satisfactorily, requires shorter time for cleaning and is easy to handle.
The test socket for a semiconductor device according to the present invention having contact members which lie between ball-shaped external terminals projected from a surface of the semiconductor device and contact pads of the semiconductor test circuit to make them conductive to each other wherein each of said contact member comprises blade-shaped contact members in contact with one of said external terminals, a positioning member for positioning said blade-shaped contact members having positioning holes into which said blade-shaped contact members are inserted, and a conductive elastic contactor having a top portion which is in contact with said blade-shaped contact member positioned by said positioning member and a bottom portion of which is in contact with one of said contact pads.
Further, in the test socket for a semiconductor device according to the present invention, the blade-shaped contact members have a plurality of blades arranged so that their outer surfaces form a circular surface and that ridgelines of the blades become gradually low from the outer peripheral surfaces of the circular arrangement toward the center thereof and intersect each other at a bottom part.
Furthermore, in the test socket of a semiconductor device according to the present invention, the blade-shaped contact member has a flange formed at its bottom which engages a lower surface of the positioning member and prevents the blade-shaped contact member from being get out of the positioning holes upward, when they are inserted into the positioning holes of the positioning members.
Furthermore, in the test socket for a semiconductor device of the present invention, the blade-shaped contact member has a substantially flat bottom surface, which is in contact with a top of the elastic contactors.
Furthermore, in the test socket for a semiconductor device according to the present invention, the blade-shaped contact members are installed so as to be removable from the elastic contactors.
Furthermore, in the test socket for a semiconductor device according to the present invention, the elastic contactors are made of a conductive resin and are embedded in an insulating base at a predetermined pitch.
Furthermore, in the test socket for a semiconductor device according to the present invention, the insulating base supports the elastic contactors so that both ends thereof are projected from upper and lower surfaces of the insulating base.
Furthermore, in the test socket for a semiconductor device according to the present invention, either one of the bottom of the blade-shaped contact member and the top of the elastic contactor has either one of a convexity and concavity so that they are fit into each other.
Furthermore, in the test socket for a semiconductor device according to the present invention, the positioning members having the positioning openings position the contact members and elastic contactors for the external terminals and contact pads.
Further, the test socket for a semiconductor device according to the present invention having contact members which lie between a plurality of ball-shaped external terminals projected from a surface of the semiconductor device and contact pads of the semiconductor test circuit to make them conductive to each other wherein each of said contact member comprises a blade-shaped contact members in contact with one of said external terminals, a positioning member for holding the blade-shaped contact members, and a plurality of conductive elastic contactors having a top portion which is in contact with one of said blade-shaped contact members positioned by said positioning member and a bottom portion of which is in contact with one of said contact pads.
Further, in the test socket for a semiconductor device according to the present invention, the blade-shaped contact members have a plurality of blades arranged so that their outer surfaces form a circular surface and that ridgelines of the blades become gradually low from the outer peripheral surfaces of the circular arrangement toward the center thereof and intersect each other at a bottom part.
Furthermore, in the test socket for a semiconductor device according to the present invention, a plurality of positioning holes are formed in the positioning members and the blade-shaped contact member has a flange formed at its bottom which engages a lower surface of the positioning member and prevents the blade-shaped contact member from being get out of the positioning holes upward, when they are inserted into the positioning holes of the positioning members.
Furthermore, in the test socket of the semiconductor device of the present invention, the blade-shaped contact member has a substantially flat bottom surface, which is in contact with a top of the elastic contactors.
Furthermore, in the test socket for a semiconductor device according to the present invention, the elastic contactors are made of a conductive resin and are embedded in an insulating base at a predetermined pitch.
The test socket for a semiconductor device according to the present invention comprises a frame plate having a space for housing the semiconductor device at a center portion thereof, a positioning member in contact with a bottom surface of the frame plate which is arranged so that a part of an upper surface thereof is exposed in the space for housing the semiconductor device, a plurality of blade-shaped contact members fixedly received in a plurality of positioning holes formed in the positioning member, an insulating base arranged so as to be in contact with a bottom surface of the positioning member, a plurality of elastic contactors embedded in an insulating base at a predetermined pitch, and a board arranged in contact with a bottom surface of the insulating base on which the semiconductor test circuit is formed.
Furthermore, in the test socket for a semiconductor device according to the present invention, positioning pins are fixed to the frame plate penetrating through the positioning member, insulating base, and the board on which the semiconductor test circuit are formed.